扬子克拉通西部砂矿型金刚石多晶的同步辐射研究及意义

Synchrotron Radiation Study of the Polycrystalline Diamond from Western Yangtze Craton and Its Significance

基于金刚石多晶形成过程的复杂性、制样的困难性等在较大程度上制约了人们对其成核、生长等结晶过程及意义等的深入理解,采用同步辐射技术对扬子克拉通的金刚石多晶进行同步辐射显微红外光谱、显微红外光谱成像等方面的研究。金刚石多晶的同步辐射研究表明,金刚石多晶研究样品总体属于Ⅰ型金刚石,其总氮含量(NT)约为500～1 300μg·g^(-1),对氮心的含量(NA)约为300～700μg·g^(-1),四氮心的含量(NB)约为150～550μg·g^(-1)。金刚石多晶在地幔中的停留时间约介于0. 06～0. 12 Ga;样品的生长经历了多个生长中心先分别生长,后连聚成多晶再生长的过程,且整个多晶体的结晶中心区形成后,晶体优先往有利于稳固结晶中心的方向生长、再各向生长之过程。同时,金刚石多晶的生长在各时期内呈各向差异生长而非均匀生长,且存在间歇性停止生长的现象。

With its high brightness and high collimation,the application of synchrotron radiation micro-infrared spectroscopy in polycrys talline diamond can significantly improve the accuracy of the analysis of nitrog en concentration and the residence time in the mantle.The results of synchrotro n radiation micro-infrared mapping of the polycrystalline diamond demonstrated that nitrogen impurity in the sample had high content(500~1 300μg·g^-1)and high aggregation,which indicated that the diamonds from western Yangtze craton are type IaAB.The residence time in mantle of the sample was between 0.0 6 to 0.12 Ga.In general,the sample had different growth zones and multiple diamond grains which crystallize early respectively and aggregate later.In additi on,some of the grains briefly ceased to grow during the polycrystalline diamond formation which formed in a volatile material situation.